Nanotube wiring

ABSTRACT

This invention concerns a novel method for surface derivatization of electrode materials for Li-ion batteries. The derivatization is based on adsorption of a composite assembly consisting of amphiphilic redox active molecule attached to single walled carbon nanotube (SWCNT). Its role consists in the enhancement of electronic conductivity of electrode materials, such as phosphate olivines, without requesting any significant increase of the electrode volume and mass. The SWCNT is linked to the redox molecule via non-covalent or covalent interaction with the hydrophobic part of the molecule or electrostatic interaction. The hydrophilic part of the molecule serves as the anchoring site for surface modification of the electrode active material. The redox potential of the molecule is close to the redox potential of the electrode active material. The adsorbed assembly of redox-molecule &amp; SWCNT thus improves the charge transfer from a current collector to the electrode active material.

DESCRIPTION OF PRIOR ART

The lithium insertion materials in commercial electrochemical cellscomprise 2˜25 wt. %, typically 10 wt. % conductive additives. Theseconductive agents do not participate in the redox reactions andtherefore represent inert mass reducing the energy storage capacity ofthe electrode. This situation is especially severe as the lithiuminsertion material or its de-intercalated state has very poor electronicconductivity as for olivine cathode materials. The advent of olivinephosphates as novel cathode materials for Li-ion batteries stems fromthe pioneering work of Goodenough et al.^([1]), who had first reportedon two generic structures, viz. LiFePO₄ and LiMnPO₄ as well as the mixedphases, LiFe_(x)Mn_(1-x)PO₄ (0<x<1). Both materials are very poorelectronic conductors; the reported conductivities of LiFePO₄ andLiMnPO₄ are (˜10⁻⁸ to 10⁻⁹) S/cm and (<10⁻¹⁰ to 3·10⁻⁹) S/cm,respectively^([2-4]). Ceder et al.^([5]) have measured the optical bandgap of LiFePO₄ to be 3.8-4.0 eV, which would account for negligibleconcentration of intrinsic charge carriers. Therefore the electroniccharge cannot be transported by delocalized electrons in the olivineconduction band, but via localized polarons at the transition metal,whose mobility is a thermally activated (hoping) process. Recently,Nazar et al.^([6]) have pointed out that the polaron hopping is stronglycorrelated with the Li⁺ transport. Enhancement of the electronicconductivity of LiMPO₄ (M=Mn, Fe) requires proper engineering of thematerial morphology^([2,7-10]) and surface modification, while thecarbon coating is the obvious strategy^([4,8,10-13]). An alternativepathway is based on the doping of LiFePO₄ by supervalent cations, suchas Zr⁴⁺ and Nb⁵⁺ at the Li⁺ site^([14]). Eventually, the conductivecoating on LiFePO₄ olivine might not be a pure elemental carbon, butphosphides or phosphocarbides as demonstrated by Nazar et al.^([3]) bythe EDX elemental map of grain boundaries. In this particular case, thephosphides Fe₂P and Fe₇₅P₁₅C₁₀ were assumed, but the presence ofelemental carbon can also be convincingly demonstrated by Ramanspectroscopy^([8]).

In the conventional solid state synthesis of LiMPO₄ (M=Mn, Fe), carbonis added to the precursor mixture composed of a stoichiometric amountsof the corresponding Li-, M- and PO₄ ³⁻ salts[4,11]. During thesynthesis, carbon simultaneously acts as a reductant, avoiding theformation of M³⁺ and also as a separator, blocking the growth ofcrystals^([11]). The suppression of crystal growth by carbon manifestsitself by the formation of particles in the range 60-100 nm. Li etal.^([11]) reported that LiMnPO₄, which was synthesized in this way,delivered 140 mAh/g at 0.28 mA/cm². Unfortunately this promising resultwas not reproduced by others^([4,13]), and the cited paper^([11])remains controversial.

LiMPO₄ (M=Mn, Fe) can also be prepared at low-temperatures by directprecipitation from aqueous solutions^([2,10,13]). In this case, thecarbon coating can be made via subsequent ball-milling with acetyleneblack^([10,13]). This strategy provided particle sizes between 100-200nm and BET areas 23-13 m²/g^([13]). Obviously, the particle sizes oflow-temperature (“chimie-douce”) olivine^([2,10,13]) are, actually,similar to those of olivine from the solid state reaction with carbonadditive^([4]). Presumably, the smallest particles of LiMnPO₄ (ca. 50nm) were prepared in thin films by electrostatic spray deposition^([9]).However, their discharge capacities were found to be only ca. 20 mAh/gat slow cyclic voltammetry^([9]). We could speculate that this accountsfor uncontrolled carbon coating (if any) in this particular case. Theoptimized carbon-coated LiMnPO₄ materials with particle sizes around 130nm exhibited 156 mAh/g at C/100 and 134 mAh/g at C/10^([10]).

Obviously, the slow polaron mobility in LiMPO₄ is a fundamental problem,which can be, presumably minimized by decreasing the particle size andoptimized decoration of particles with conductive carbon.

In the PCT/IB2006/051781 is described novel strategy forcharging/discharging of virtually insulating cathode materials likeLiMPO₄ called molecular wiring. It is based on an efficient crosssurface electron/hole transport in self-assembled redox active moleculesadsorbed on the LiMPO₄ surface. In the European patent application 06112 361.8 is described a similar method, called redox targeting ofcathode materials. It adopts the same philosophy of charge transport byredox-active molecules, but the molecules do not act here in the form ofadsorbed monolayer, but are dissolved in the electrolyte solution. Thisconcept is attractive due to larger currents, which can be drawn in theredox targeting process, but the redox targeting is complicated by aneed of a special separator between anode and cathode. This separatormust allow the fast Li⁺ transport, but it must simultaneously block thetransport of redox-targeting molecules to the anode.

FIELD OF THE INVENTION

This invention concerns electrochemically addressable lithium insertionelectrode systems for electrochemical cells using non-aqueous organicelectrolytes, quasi-solid gel electrolytes, solid electrolytes, or thelike and in particular the use of said electrolytes in combination withporous electrode materials, i.e. doped or non-doped nanoparticles orsub-microparticles of lithium insertion materials and redox activecompounds.

This invention also concerns the configuration of the electrochemicalcell containing the redox active compounds attached to SWCNT.

Here we show a novel concept called nanotube wiring, which is based onanchoring of the redox relay—charge transport by redox activemolecules—attached to SWCNT, which can improve the conductivity of thecathode material in Li-ion battery. The amphiphilic redox activecompound contains hydrophobic and hydrophilic parts in the molecule;hence it can act as surfactants dispersing SWCNT. The hydrophobic part(e.g. aliphatic chain) serves for anchoring of SWCNT via non-covalentbonds. The hydrophilic part is represented by either ionic or unchargedpolar functional groups (e.g. COOH), which interact with the surface ofthe electrode active material. Because the adsorbed assembly does notoccupy any significant extra volume of the whole electrode system, theelectrode composite provides excellent energy density of theelectrochemical cell. This concept is attractive due to larger currents,which can be drawn similar as in the redox targeting process, describedin the European patent application 06 112 361.8 but comparing todescribed process we do not need of a special separator between anodeand cathode. The novel idea uses SWCNT modified by redox relay, which isfurther adsorbed on the electrode active material. The redox relay isthus localized on the electrode and cannot react with the oppositeelectrode.

SUMMARY OF THE INVENTION

It has been discovered that some amphiphilic redox active moleculesinteract to SWCNT can further anchor with the surface of electrodeactive material such as LiFePO₄ (olivine). The assembly of redoxmolecule and SWCNT thus covers the surface of the active material,forming an electrochemically addressable electrode system. For cathodiclithium insertion material upon positive polarization the donor redoxactive compound (D) will be oxidized at current corrector and charges(holes) will be transported from the current collector to the lithiuminsertion material by the oxidized form of the redox active compound(D⁺). As the redox potential of the redox active compound is higher ormatches closely the Fermi level of the lithium insertion material, D⁺will be reduced by the lithium insertion material. Electrons and lithiumions will be withdrawn from it during battery charging. By contrast,during the discharging process, the oxidized species are reduced atcurrent collector and charges (electrons) are transported from thecurrent collector to the lithium insertion material by the redox activecompound (D). Lithium ions and electrons are injected into the solid, asthe redox potential of the redox active compound is lower or matchesclosely the Fermi level of the lithium insertion material.

The cell is composed of two compartments, where the cathodic compartmentcomprises a cathodic lithium insertion material and redox activecompound(s); the anodic compartment comprises an anodic lithiuminsertion material and redox active compound(s). These two compartmentsare separated by a separator. Compared to the whole electrode system,the redox active adsorbate does not occupy any significant extra volumeof the whole electrode system. Hence with respect to prior art, thepresent invention allows reducing greatly the volume of the conductiveadditives resulting in a much improved energy storage density. The redoxadsorbate is not soluble in the working electrolyte so the use of aspecial separator as described in the European patent application 06 112361.8 is not necessary.

-   -   According to the present invention, a redox active molecule is        attached to the SWCNT backbone by non-covalent bonding. A redox        active centre (D) may be an organic compound or a metal complex        having suitable redox potential as that of the battery material.        In preferred configuration the redox active metal complex or        organic compound (D) is localized between the SWCNT surface and        the surface of electrode active material.

SWCNT-D-[M]  (I)

-   -   Wherein [M] represents schematically the electrode material

DEFINITIONS

As used herein, the term “lithium insertion material” refers to thematerial which can host and release lithium ions reversibly. If thematerials lose electrons upon charging, they are referred to as“cathodic lithium insertion material”. If the materials acquireelectrons upon charging, they are referred to as “anodic lithiuminsertion material”.

As used herein, the term “donor-type redox active compound” refers tothose compounds that are present in the cathodic compartment of thecell, and act as molecular relay transporting charges between currentcollector and cathodic lithium insertion material uponcharging/discharging. On the other hand, the term “acceptor-type redoxactive compound” refers to the molecules that present in the anodiccompartment of the cell, and act as molecular relay transporting chargesbetween current collector and anodic lithium insertion material uponcharging/discharging.

DETAILED DESCRIPTION OF THE INVENTION

A redox active centre may be an organic compound or a metal complexhaving suitable redox potential as that of the lithium insertionmaterial.

In a preferred configuration the redox active centre is of the typegiven below,

D-ΠRal) or D-(Ral)  (II)

-   -   wherein Π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that Π may bear        more than one substituent Ral.    -   The π system Π may be an unsaturated chain of conjugated        double or triple bonds of the type

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20.    -   According to a preferred embodiment, D is selected from benzol,        naphtaline, indene, substituted triarylamine, fluorene,        phenantrene, anthracene, triphenylene, pyrene, pentalene,        perylene, indene, azulene, heptalene, biphenylene, indacene,        phenalene, acenaphtene, fluoranthene, and heterocyclic compounds        pyridine, pyrimidine, pyridazine, quinolizidine, quinoline,        isoquinoline, quinoxaline, phtalazine, naphthyridine,        quinazoline, cinnoline, pteridine, indolizine, indole,        isoindole, carbazole, carboline, acridine, phenanthridine,        1,10-phenanthroline, thiophene, thianthrene, oxanthrene, and        derivatives thereof, optionally be substituted.

According to a preferred embodiment, D is selected from structures offormula (1-11) given below:

in which each of Z¹, Z² and Z³ is the same or different and is selectedfrom the group consisting of O, S, SO, SO₂, NR¹, N⁺(R^(1′))(^(1″)),C(R²)(R³), Si(R^(2′))(R^(3′)) and P(O)(OR⁴), wherein R¹, R^(1′) andR^(1″) are the same or different and each is selected from the groupconsisting of hydrogen atoms, alkyl groups, haloalkyl groups, alkoxygroups, alkoxyalkyl groups, aryl groups, aryloxy groups, and aralkylgroups, which are substituted with at least one group of formula—-N⁺(R⁵)₃ wherein each group R⁵ is the same or different and is selectedfrom the group consisting of hydrogen atoms, alkyl groups and arylgroups, R², R³, R^(2′) and R^(3′) are the same or different and each isselected from the group consisting of hydrogen atoms, alkyl groups,haloalkyl groups, alkoxy groups, halogen atoms, nitro groups, cyanogroups, alkoxyalkyl groups, aryl groups, aryloxy groups and aralkylgroups or R² and R³ together with the carbon atom to which they areattached represent a carbonyl group, and R⁴ is selected from the groupconsisting of hydrogen atoms, alkyl groups, haloalkyl groups,alkoxyalkyl groups, aryl groups, aryloxy groups and aralkyl groups.

Preferred p-type redox active compounds have the following structure:

Triarylamine Derivatives

n=0 to 20

X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ A=F or Cl or Br I or NO₂ orCOOR or Alkyl (C₁ to C₂₀) or CF₃ or COR or OCH₃ or H B=F or Cl or Br Ior NO₂ or COOR or Alkyl (C₁ to C₂₀) or CF₃ or COR or OCH₃ A=B or A≠B

n=0 to 20

R=H Or C₁ to C₂₀ X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂Phenothiazine Derivatives, Carbazole Derivatives

n=0 to 20

X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ Y=N or O or S R₁, R₂, R₃, R₄can be F or Cl or Br I or NO₂ or COOR or Alkyl (C₁ to C₂₀) or CF₃ or CORor OCH₃ or H Pyridine N-Oxide Derivatives

Wherein A and B are same or different from H, OR, Cl, Br, F, I, NO2,CF3, COCF3, R is H or (CH₂)_(p)-E-(CH₂)_(m)—Acc (p=0 to 24, linear orbranched or with cycles; n=0 to 24, m=0 to 24, linear or branched orwith cycles; E is —CH═CH—, or —C≡C—, or —OCH₂CH₂—, and Acc is PO₃H₂ orCO₂H or SO₃H or CONHOH or PO₄H₂ or SO₄H₂

Phenothiazine Derivatives

Wherein X and Y are same or different from H, OR, Cl, Br, F, I, NO2,CF3, COCF3, R is H or (CH₂)_(p)-E-(CH₂)_(m)—Acc (p=0 to 24, linear orbranched or with cycles; n=0 to 24, m=0 to 24, linear or branched orwith cycles; E is —CH═CH—, or —C≡C—, or —OCH₂CH₂—, and Acc is PO₃H₂ orCO₂H or SO₃H or CONHOH or PO₄H₂ or SO₄H₂

Phenol Derivatives

Wherein A, B and C are same or different from H, OR, Cl, Br, F, I, NO2,CF3, COCF3, linear or branched alkyl group from 1 to 20 carbon atoms,R is H or (CH₂)_(p)-E-(CH₂)_(m)—Acc (p=0 to 24, linear or branched orwith cycles; n=0 to 24, m=0 to 24, linear or branched or with cycles; Eis —CH═CH—, or —C≡C—, or —OCH₂CH₂—, and Acc is PO₃H₂ or CO₂H or SO₃H orCONHOH or PO₄H₂ or SO₄H₂

-   -   Alternatively a redox active centre may be a metal complex        having suitable redox potential as that of the lithium insertion        material.    -   In metal complexes as redox active centers, the preferred        ligands coordinated to the metal, according to the invention are        metal complexes having a formula selected from

wherein M=Fe or Ru or Osn=0 to 20

X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ or SO₄H₂ P=F or Cl or Br or Ior NO₂ or CN or NCSe or NCS or NCO

Wherein B=alkyl (C₁ to C₂₀) or HR, R₁, R₂ is same or different from COORS or PO₃R₃ or SO₃R₃ or CONR₃OR₃or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Br or I orNR₃ or a liniar or branched alkyl (C₁ to C₂₀) or H (where R₃ is an alkyl(C₁ to C₂₀) or H) or comprises an additional π system located inconjugated relationship with the primary π system, the said substituentis of the type

—R=πRal) or -(Ral)

-   -   wherein π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that π may bear        more than one substituent Ral.    -   wherein at least one of substituents —R, —R₁, —R₂ is of formula        (1), (2) or (3)

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is a H or —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20.-   wherein the other one(s) of substituent(s) —R, —R₁, —R₂ is (are) the    same or a different substituent of formula (1), (2) or (3), or is    (are) selected from —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F,    I, CF3, or —N(R₃)₂, wherein R₃ is a liniar or branched alkyl of 1 to    20 carbon atoms.

M=Fe or Ru or Os X=F or Cl or Br or I or NO₂ or CN or NCSe or NCS or NCO

Wherein B=liniar or branched alkyl (C₁ to C₂₀) or HR, R₁, R₂ is same or different from COOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Br or I orNR₃ or a liniar or branched alkyl (C₁ to C₂₀) or H (where R₃ is an alkyl(C₁ to C₂₀) or H) or comprises an additional π system located inconjugated relationship with the primary π system, the said substituentis of the type

—R=πRal) or -(Ral)

-   -   wherein π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that π may bear        more than one substituent Ral.    -   wherein at least one of substituents —R, —R₁, —R₂ is of formula        (1), (2) or (3)

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is a H or —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20.-   wherein the other one(s) of substituent(s) —R, —R₁, —R₂ is (are) the    same or a different substituent of formula (1), (2) or (3), or is    (are) selected from —H, —OH, —R₃, —OR₃, COOH, COCF₃, CN, Br, Cl, F,    I, CF3, or —N(R₃)₂, wherein R₃ is a liniar or branched alkyl of 1 to    20 carbon atoms.

Wherein B=alkyl (C₁ to C₂₀) or HR, R₁, R₂ may be same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or alkyl (C₁ to C₂₀) or H where R₃ is an alkyl (C₁ to C₂₀)or H R, R₁, R₂ is same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or a liniar or branched alkyl (C₁ to C₂₀) or H (where R₃ isa linear or branched alkyl (C₁ to C₂₀) or H) or comprises an additionalπ system located in conjugated relationship with the primary π system,the said substituent is of the type

—R=πRal) or -(Ral)

-   -   wherein π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that π may bear        more than one substituent Ral.    -   wherein at least one of substituents —R, —R₁, —R₂ is of formula        (1), (2) or (3)

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is a H or —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20.-   wherein the other one(s) of substituent(s) —R, —R₁, —R₂ is (are) the    same or a different substituent of formula (1), (2) or (3), or is    (are) selected from —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F,    I, CF3, or —N(R₃)₂, wherein R₃ is a liniar or branched alkyl of 1 to    20 carbon atoms.

Wherein M=Fe or Ru or Os

B=alkyl (C₁ to C₂₀) or HR, R₁, R₂ may be same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or alkyl (C₁ to C₂₀) or H where R₃ is an alkyl (C₁ to C₂₀)or H R, R₁, R₂ is same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or a liniar or branched alkyl (C₁ to C₂₀) or H (where R₃ isa linear or branched alkyl (C₁ to C₂₀) or H) or comprises an additionalπ system located in conjugated relationship with the primary π system,the said substituent is of the type

—R=πRal) or -(Ral)

-   -   wherein π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that π may bear        more than one substituent Ral.    -   wherein at least one of substituents —R, —R₁, —R₂ is of formula        (1), (2) or (3)

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is a H or —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20.-   wherein the other one(s) of substituent(s) —R, —R₁, —R₂ is (are) the    same or a different substituent of formula (1), (2) or (3), or is    (are) selected from —H, —OH, —R₃, —OR₃, COOH, COCF₃, CN, Br, Cl, F,    I, CF3, or —N(R₃)₂, wherein R₃ is a liniar or branched alkyl of 1 to    20 carbon atoms.

M=Fe or Ru or Os

n=0 to 20

X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ or SO₄H₂ P=F or Cl or Br or Ior NO₂ or CN or NCSe or NCS or NCO

Wherein B=alkyl (C₁ to C₂₀) or HR, R₁, R₂ may be same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or alkyl (C₁ to C₂₀) or H where R₃ is an alkyl (C₁ to C₂₀)or H R, R₁, R₂ is same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or a liniar or branched alkyl (C₁ to C₂₀) or H (where R₃ isa linear or branched alkyl (C₁ to C₂₀) or H) or comprises an additionalπ system located in conjugated relationship with the primary π system,the said substituent is of the type

—R=πRal) or -(Ral)

-   -   wherein π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that π may bear        more than one substituent Ral.    -   wherein at least one of substituents —R, —R₁, —R₂ is of formula        (1), (2) or (3)

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is a H or —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20.-   wherein the other one(s) of substituent(s) —R, —R₁, —R₂ is (are) the    same or a different substituent of formula (1), (2) or (3), or is    (are) selected from —H, —OH, —R₃, —OR₃, COOH, COCF₃, CN, Br, Cl, F,    I, CF₃, or —N(R₃)₂, wherein R₃ is a liniar or branched alkyl of 1 to    20 carbon atoms.

M=Fe or Ru or Os

n=0 to 20

X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ or SO₄H₂ P=CN or NCSe or NCSor NCO

Wherein B=alkyl (C₁ to C₂₀) or HR, R₁, R₂ may be same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or alkyl (C₁ to C₂₀) or H where R₃ is an alkyl (C₁ to C₂₀)or H R, R₁, R₂ is same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or a liniar or branched alkyl (C₁ to C₂₀) or H (where R₃ isa linear or branched alkyl (C₁ to C₂₀) or H) or comprises an additionalπ system located in conjugated relationship with the primary π system,the said substituent is of the type

—R=πRal) or -(Ral)

-   -   wherein π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that π may bear        more than one substituent Ral.    -   wherein at least one of substituents —R, —R₁, —R₂ is of formula        (1), (2) or (3)

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is H or —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20.-   wherein the other one(s) of substituent(s) —R, —R₁, —R₂ is (are) the    same or a different substituent of formula (1), (2) or (3), or is    (are) selected from —H, —OH, —R₃, —OR₃, COOH, COCF₃, CN, Br, Cl, F,    I, CF₃, or —N(R₃)₂, wherein R₃ is a liniar or branched alkyl of 1 to    20 carbon atoms.

M=Fe or Ru or Os

n=0 to 20

X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ or SO₄H₂

P=CN or NCSe or NCS or NCO or pyrazine.

Wherein B=alkyl (C₁ to C₂₀) or HR, R₁, R₂ may be same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or alkyl (C₁ to C₂₀) or H where R₃ is an alkyl (C₁ to C₂₀)or H R, R₁, R₂ is same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or a liniar or branched alkyl (C₁ to C₂₀) or H (where R₃ isa linear or branched alkyl (C₁ to C₂₀) or H) or comprises an additionalπ system located in conjugated relationship with the primary π system,the said substituent is of the type

—R=πRal) or -(Ral)

-   -   wherein π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that π may bear        more than one substituent Ral.    -   wherein at least one of substituents —R, —R₁, —R₂ is of formula        (1), (2) or (3)

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is a H —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20.-   wherein the other one(s) of substituent(s) —R, —R₁, —R₂ is (are) the    same or a different substituent of formula (1), (2) or (3), or is    (are) selected from —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F,    I, CF3, or —N(R₃)₂, wherein R₃ is a liniar or branched alkyl of 1 to    20 carbon atoms.

Wherein B=alkyl (C₁ to C₂₀) or HR, R₁, R₂ may be same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or alkyl (C₁ to C₂₀) or H where R₃ is an alkyl (C₁ to C₂₀)or H R, R₁, R₂ is same or different from COOR₃ or PO₃R₃ or SO₃R₃ orCONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Bror I or NR₃ or a liniar or branched alkyl (C₁ to C₂₀) or H (where R₃ isa linear or branched alkyl (C₁ to C₂₀) or H) or comprises an additionalπ system located in conjugated relationship with the primary π system,the said substituent is of the type

—R=πRal) or -(Ral)

-   -   wherein π represents schematically the π system of the        aforesaid substituent, Ral represents an aliphatic substituent        with a saturated chain portion bound to the π system, and        wherein q represents an integer, indicating that π may bear        more than one substituent Ral.    -   wherein at least one of substituents —R, —R₁, —R₂ is of formula        (1), (2) or (3)

-   -   wherein p is an integer from 0 to 20,    -   wherein Rar is a H or monocyclic or oligocyclic aryl from C6 to        C22,    -   wherein -Ral is —R1 or —O—R1 or —N(R1)₂ or —NHR1 or

-   wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,    —CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<10.-   wherein the other one(s) of substituent(s) —R, —R₁, —R₂ is (are) the    same or a different substituent of formula (1), (2) or (3), or is    (are) selected from —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F,    I, CF3, or —N(R₃)₂, wherein R₃ is a liniar or branched alkyl of 1 to    20 carbon atoms.

Example 1 Methods

LiFePO₄ was synthesized by a variant of solid state reaction^([15])employing FeC₂O₄.2H₂O and LiH₂PO₄ as precursors. Their stoichiometricamounts were mixed and ground in a planetary ball-milling machine for 4h. Then the powder was calcined in a tube furnace with flowing Ar—H₂(92:8 v/v) at 600° C. for 24 h. After cooling down to room temperature,the sample was ground in agate mortar. The BET surface area of thepowder was ca. 5 m²/g with an average particle size of 400 nm. X-raydiffraction confirmed the phase purity. The Ru-bipyridine complex,NaRu(4-carboxylic acid-4′-carboxylate(4,4′-dionyl-2,2′bipyridine)(NCS)₂,coded as Z-907Na was synthesized as described elsewhere^([16]). Singlewalled carbon nanotubes were grown by catalytic laser ablation method.The average diameter of tubes was determined by Raman and Vis-NIRspectroscopy to be ca. 1.3-1.4 nm. Other chemicals were from commercialsources and were used as received.

SWCNT were dispersed with solutions of surfactants (either pyrenebutanoic acid in dimethylformamide (DMF) or Z-907Na inacetonitrile+tert-butanol (1:1) (AN/t-BuOH) by sonication. The optimizedsynthetic protocol for Z-907Na was as follows: 9 mg of SWCNT wassonicated for 2 hours with 10 mL of 6·10⁻⁴ M Z-907Na inacetonitrile+t-butanol (1:1). The resulting black-brown solution wascentrifuged at 5000 rpm for 1 hour, while ca. 4 mg of undissolved carbonremained as a sediment. This working solution (abbreviated further asZ-907Na/SWCNT) was stable for at least weeks at room temperature withoutprecipitation. Hence, the solution contained ca. 5 mg of dispersed SWCNT(417 μmol) and 6 μmol of Z-907Na (molar ratio C/Z-907Na≈70). The olivineLiFePO₄ (200 mg) was mixed with several portions (0.5-0.7 mL) of thisworking solution. At the initial stages, the supernatant turned tocolorless within several seconds after mixing. After each addition ofthe Z-907Na/SWCNT solution, the slurry was centrifuged, supernatantseparated and a next portion of the solution was added. This procedurewas repeated until the supernatant did not decolorize. The total amountof applied solution was 1.5 mL. Finally the powder was washed withAN/t-BuOH and dried at room temperature. The same synthetic protocol wasalso adopted also for surface derivatization of LiFePO₄ withpyrenebutanoic acid/SWCNT.

Electrodes were prepared by mixing the powder of surface derivatizedLiFePO₄ with 5 wt % of polyvinylidene fluoride (PVDF) dissolved inN-methyl-2-pyrolidone. The resulting homogeneous slurry was thendoctor-bladed onto F-doped conducting glass (FTO) and dried at 100° C.overnight. Alternatively the slurry was coated on alumina currentcollector and dried at 100° C. overnight. The typical film mass was1.5-2 mg/cm². Blank electrodes from pure LiFePO₄ were prepared in thesame way for reference experiments. A second reference material was acarbon-coated LiFePO₄ (Nanomyte BE-20 from NEI Corporation, USA). Theelectrode was assembled in the electrochemical cell with Li referenceand counter electrodes or alternatively in the Swagelok cell with Linegative electrode.

Methods

Vis-NIR spectra were measured at Varian Cary 5 spectrometer in 2 mmglass optical cells. The measurement was carried out in transmissionmode with integrating sphere. Electrochemical experiments employed anAutolab PGSTAT 30 potentiostat. The electrolyte was 1 M LiPF₆ inethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1, v:v). Thereference and counter electrodes were from Li-metal.

Results and Discussion

FIG. 1 shows the Vis-NIR spectra of 6×10⁻⁴ M solution of Z-907Na complexand the working solution Z-907Na/SWCNT. In the latter case, we detectedthe characteristic features of carbon nanotubes. Semiconducting SWCNTare characterized by optical transitions between van Hove singularitiesat ca. 0.7 eV and 1.3 eV for the first and second pair of singularities,respectively. Metallic tubes manifest themselves by a transition at1.8-1.9 eV, which corresponds to the first pair of Van Hovesingularities. The main peak of Z-907Na occurs at ca. 2.35 eV, and it isblue shifted by ca. 50 meV in the SWCNT-containing solution (FIG. 1).Obviously, the Z-907Na complex acts as an efficient surfactant forSWCNT, due to the presence of hydrophobic aliphatic C9 chains (Scheme1), which interact with the carbon tube surface. There are many othermolecules reported for solubilization of SWCNT, the most popular beingsodium dodecyl sulfate^([17]), but, to the best of our knowledge, thesolubilization of SWCNT by Ru-bipyridine complexes is here demonstratedfor the first time.

FIG. 2 (left chart) shows the cyclic voltammogram of a pure (carbonfree) LiFePO₄ (bonded with 5% PVDF), which was treated by dip-coatinginto 6×10⁻⁴ mol/L solution of Z-907Na for 3 hours, rinsed with AN/t-BuOHand dried in vacuum at room temperature. The right chart plots analogousdata for pure LiFePO₄ electrode, which was treated with Z-907Na/SWCNTsolution in the same way. We see a plateau anodic current, whichindicates the so-called “molecular wiring” of LiFePO₄ ^([18]). TheZ-907Na complex (as in Scheme 1, can transport electronic charge viasurface percolation in adsorbed monolayer even on insulating surfaceslike Al₂O₃ ^([19]). Here, the NCS groups act as mediators for thesurface-confined hole percolation, and the bipyridine ligands transportelectrons. The hole diffusion coefficient within adsorbed Z-907Na was ofthe order of 10⁻⁹ cm²/s above the charge percolation threshold, ca. 50%of surface coverage^([19]).

The effect of molecular wiring was recently applied to the LiFePO₄electrode material, which can be wired by4-(bis(4-methoxyphenyl)amino)benzylphosphonic acid^([20]). In this case,the cross-surface hole percolation was followed by interfacial chargingand discharging of LiFePO₄ with Li⁺ ions^([20]). Our data confirm thatthe hole-transport wiring is possible also with the Z-907Na complex,while a similar anodic current (exceeding 0.2 mA/cm²) can be wired tothe LiFePO₄ electrode at 0.1 V/s. The formal redox potential of Z-907Naadsorbed on inert TiO₂ surface was about 3.5 V vs. Li/Li^(+[19,21]),which is just sufficient for the anodic wiring of LiFePO₄ (redoxpotential 3.45 V vs. Li/Li⁺) but not for cathodic wiring^([20]). Ourdata on FIG. 2 also confirm that the COOH/COONa are suitable anchoringgroups for LiFePO₄, similar to the phosphonic acid anchoring groupemployed previously^([20]). The total anodic charge was between 2 to 4mC (0.4 to 0.7 mAh/g) for the electrode in FIG. 2 (left chart) at thegiven scan rates. This charge was not much larger at slower scanning andmoreover, the electrode was unstable during repeated cycling at slowerscan rates. The molecular wiring via adsorbed Z-907Na is sensitive toimperfections in the surface layer, which hamper the hole percolation.

FIG. 2 (right chart) shows a variant of the previous experiment, wherethe LiFePO₄ film was treated by dip-coating into Z-907Na/SWCNT solution.Surprisingly, the anodic current is now considerably smaller, which maybe due to poor accessibility of the pores in the pre-deposited LiFePO₄layer for SWCNT. As the carbon tubes are typically 1-10 μm long, theycannot easily interpenetrate the compact porous solid. Hence, theZ-907Na/SWCNT assemblies reside prevailingly on top of the LiFePO₄layer. We may assume that either some free complex (Z-907Na) may stillbe present in our working solution Z-907Na/SWCNT or may be partlyreleased from the SWCNT upon interaction with the LiFePO₄ surface. Thiscauses poor surface coverage and attenuated molecular wiring in thiscase.

However, this situation changes dramatically, if the surfacederivatization is carried out with the starting LiFePO₄ powder insteadof the doctor-bladed porous film. FIG. 3 (left chart) shows cyclicvoltammogram of this electrode compared to the voltammograms of anelectrode, which was fabricated in the same way, but instead of usingZ-907Na complex as a surfactant, the SWCNT were solubilized by pyrenebutanoic acid. Obviously, this electrode shows practically no activity,indicating that the sole carbon nanotubes do not promote thecharging/discharging of LiFePO₄. Also the electrode from carbon-coatedLiFePO₄ (Nanomyte BE-20, NEI) shows much smaller activity compared toour Z-907Na/SWCNT electrode at the same conditions. A comparativeexperiment with Z-907Na/SWCNT treated LiMnPO₄ powder also showedpractically no electrochemical activity (data not shown). Thecharging/discharging of LiFePO₄ via the surface attached Z-907Na/SWCNTassemblies was reasonably reversible, providing at 0.1 mV/s scan ratethe specific capacity of ca. 41 mAh/h for anodic process and 40 mAh/gfor cathodic process (see data on FIG. 3). The electrode was also quitestable, showing no obvious capacity fading in repeated voltammetricscans.

The exceptional properties of our Z-907Na/SWCNT electrode are furtherdemonstrated by galvanostatic charging/discharging cycle. FIG. 3 (rightchart) demonstrates that the Z-907Na/SWCNT electrode delivered at thecharge rate C/5 and cut-off potentials 4 and 2.7 V vs. Li/Li⁺ the anodiccharge of 390 mC (51 mAh/g) and the cathodic charge of 337 mC (44mAh/g). A comparative test with carbon-coated LiFePO₄ (Nanomyte BE-20,NEI) cannot be carried out due to negligible activity of this electrodeat the C/5 rate. Even at ten times slower charging, this carbon-coatedelectrode exhibits much worse performance (curve B in FIG. 3, rightchart).

The applied amount of working solution Z-907Na/SWCNT (1.5 mL; 6×10⁻⁴mol/L Z-907Na) gives the upper limit of the adsorbed Z-907Na to be 0.9μmol and the amount of adsorbed carbon (in the form of SWCNT) to be 6.3μmol per 200 mg of LiFePO₄ (See Experimental Section). The concentrationof elemental carbon from SWCNT was, therefore, less than 0.04 wt % inthe final solid material). From the BET surface area of LiFePO₄ we cancalculate that the surface coverage of Z-907Na is equivalent to aboutone molecule per 2 nm². This is not far from the monolayer coverage, ifwe take into account the usual dimensions of Ru-bipyridinemolecules^([22]).

The unprecedented activity of the electrode composite ofLiFePO₄/Z-907Na/SWCNT is obviously due to the presence of carbonnanotubes, which can quickly transport the charge mediated by Z-907Nacomplex towards the olivine surface. This beneficial role of carbonnanotubes even promotes the cathodic process. This is almost absent insole molecular wiring, due to low driving force of the redox process inZ-907Na for the reduction of Li_(1-x)FePO₄ back to the startingstoichiometric composition (FIG. 2).

Example 2 Synthesis of 12-(2,5-di-tent-butyl-4-methoxyphenoxy) dodecylphosphonic acid

Ratio of Reactants:

Reagent F.W (uma) g ml mol I 540.76 0.5 0.925 · 10⁻³ HCl_(37%) 35.5 5Method: In a 25 ml three necked round bottomed flask (equipped with acondenser) were placed 0.5 g of I dissolved in a 12N HCl water solution(5 ml). The solution was stirred at reflux temperature for about onenight. The reactor was kept in the dark. The reaction was followed by1H-NMR until the signal of CH₂ of the esters has disappeared. Then theexcess of chlorhydric acid was distilled off at reduced pressure, andthe product collected as brown viscous oil. The product was dissolvedtwo to three times in toluene and the solvent distilled off at reducedpressure. No other purification was needed. Yield: quatitative.

¹H-NMR (CDCl₃): 1.18-1.35 ppm (bm, 36H, H chain+C(CH₃)₃); 1.48 ppm (m,2H, H chain); 1.81 ppm (m, 4H, H chain); 3.80 ppm (s, 3H, OCH₃); 3.94ppm (t, 2H, OCH₂CH₂); 6.81 ppm (d, 2H, H_(ar)).

Synthetic Route:

Intermediate 11-(12-bromododecyloxy)-2,5-di-tert-butyl-4-methoxybenzene^(i)

^(i) J. Phys. Chem. B, 106 (27), (2002), 6860

Ratio of Reactants:

Reagent F.W (uma) g mol I 236.35 1 4.23 · 10⁻³ II 328 3.5 1.06 · 10⁻²NaH 24 0.11  4.6 · 10⁻³Method: In a 100 ml three necked round bottomed flask (equipped with aSchlenk cock) were placed 0.11 g of NaH in anhydrous THF (15 ml) and 1gram (4.23 mmol) of I. A gas evolution occurred for a few minutes, whenit was finished 3.5 g (10 mmol) of 1,12-dibromododecane (dissolved in 15ml of THF) were added. The mixture was stirred at room temperature forabout one hour, then the system was refluxed for 20 hours. The reactorwas kept in the dark and in a inert atmosphere (argon). Then the mixturewas cooled to room temperature and 60 ml of water were added. Theorganic phase was extracted with DCM (3×60 ml), dried with CaCl₂ and thesolvent removed under vacuum to give a slightly yellow viscous liquid.The product was purified by flash chromatography on silica gel (ethylacetate/petroleum ether 5:95), giving 1.7 g of pure (GC/MS) product(colourless liquid). Yield: 83%.

MS (EI): 482 (M+), 484 (M+2), 236; 221 (100%). ¹H-NMR (CDCl₃, t.a.):1.28-1.32 ppm (bm, 36H, H chain+C(CH₃)₃); 1.81 ppm (bm, 4H, H chain);3.76 ppm (s, 3H, OCH₃); 3.90 ppm (t, 2H, OCH₂CH₂); 4.10 ppm (t, 2H,CH₇Br); 6.81 ppm (bs, 2H, H_(ar)).

Intermediate 2 diethyl 12-(2,5-di-tent-butyl-4 methoxyphenoxy)dodecylphosphonate

Ratio of Reactants:

Reagent F.W (uma) g ml mol I 483.56 1 2.07 · 10⁻³ II 166.16 8Method: In a 25 ml three necked round bottomed flask (equipped with acondenser) were placed 1 g of I dissolved in triethylphosphite (8 ml).The solution was stirred at 120° C. for about three hour. The reactorwas kept in the dark and in a inert atmosphere (argon). Then the excessof triethylphosphite was distilled off at reduced pressure and theproduct collected as brown liquid. The purification was carried out byflash chromatography on silica gel (petrol ether/ethyl acetate 5:1). Thepure product is a colourless liquid (Yield: 85%).

MS (EI): 540 (M+); 305 (100%). ¹H-NMR (CDCl₃): 1.18-1.35 ppm (bm, 42H, Hchain+POCH₂CH₃+C(CH₃)₃); 1.71 ppm (m, 2H, H chain); 1.81 ppm (m, 4H, Hchain); 3.80 ppm (s, 3H, OCH₃); 3.94 ppm (t, 2H, OCH₂CH₂); 4.09 ppm (m,4H, POCH₂CH₃); 6.81 ppm (d, 2H, H_(ar)).

Results and Discussion

FIG. 4 shows the cyclic voltammogram of DW adsorbed on mesoscopic TiO₂electrode. DW exhibits reversible charge-transfer reaction, despite theTiO₂ is insulating in this potential region and inactive for (dark)electrochemistry. This is an evidence for cross-surface electron/holepercolation in the DW molecules. UV-spectrophotometry indicated thesurface coverage of TiO₂ with DW^(ref 23) to be 0.3 nmol/cm², whichtranslates into ≈2 molecules/nm². (The surface coverage is refereed tothe overall physical surface of the electrode material, which was 55cm²). The integrated voltammetric charge at the slowest scan (1 mV/s)was 1.51 mC, which translates into 0.28 nmol/cm². Hence, the DW makesroughly a monolayer on the TiO₂ surface, and is fully active forambipolar charge transport from the FTO support. Inset in FIG. 4 showsthat the forward peak current density, J_(p) scales with the square rootof the scan rate, v^(1/2) according to the Randles-Sevcik equation:

J _(p)=2.69.10⁵ n ^(3/2) D ₊ ^(1/2) c ₀ v ^(1/2)  (1)

(n is number of electrons). The concentration of DW in the film(thickness 2.5 μm) equals c₀=3.3.10⁻⁴ mol/cm³. From the slope of theline in FIG. 4 (inset) and Eq. (1) we can calculate the diffusioncoefficient D₊=9.10⁻¹⁰ cm²/s. This coefficient describes actually thecross surface motion of holes though the DW monolayer, and not the masstransport, because the translational motion of adsorbed molecules isobviously excluded. Therefore, the charge transfer stops, if apercolation threshold is achieved. The found D₊ is not too far from thevalue for Ru-bipyridine complex Z-907 adsorbed on TiO₂[D₊=(1.5 to4.1).10⁻⁹ cm²/s], but is by three orders of magnitude smaller than thevalue of “real” diffusion coefficient of DBB dissolved in electrolytesolution (1.6.10⁻⁶ cm²/s).

FIG. 5 shows cyclic voltammograms of DW on TiO₂. The peak-to-peaksplitting for the first scan was between 41 to 59 mV. The splitting isnarrower than 60/n mV expected for a reversible redox system insolution, which indicates the surface confinement of DW. During repeatedscanning, the integral voltammetric charge drops by ca. 2% per cycle andalso the peak-to-peak splitting increases. This illustrates that thereare certain limits of the stability of the DW/TiO₂ system at theseconditions.

FIG. 6 shows the cyclic voltammograms of DW adsorbed on LiMnPO₄electrode. The behavior is similar to that on TiO₂ (cf. FIG. 4). Inother words, LiMnPO₄ behaves like an inert (insulating) support, andmolecular wiring towards oxidative delithiation of LiMnPO₄ is absent.This is understandable because the available redox potential of DW doesnot provide enough driving force for this reaction. By using the sameevaluation routine as for TiO₂ we can calculate the diffusioncoefficient from the slope of J_(p) vs. v^(1/2) (inset in FIG. 3) to be:D₊=3.10⁻⁹ cm²/s^(Ref23). Interestingly, the cross-surface chargetransport is ca. three times faster on LiMnPO₄ compared to TiO₂. Thismight be due to different surface morphology: whereas TiO₂ is amesoporous material with statistically sintered 20-nm particles, theLiMnPO₄ consists of platelets ca. 200 nm in size, exposing the (010)faces on which the DW molecules can be assembled in a more organizedway.

Although LiMnPO₄ is intact for molecular wiring (cf. FIG. 6), thiseffect is well expressed for LiFePO₄ olivine. FIG. 7A shows that aconstant current flows at potentials above ca. 4.1 V. This plateau(“wiring current”) is indicative for subsequent chemical reaction of theoxidized molecule (DW⁺) with LiFePO₄ olivine causing its oxidativedelithiation:

DW⁺+LiFePO₄→DW+Li⁺+FePO₄  (2)

Interestingly, at faster scanning (200 mV/s) we may trace also theparent peaks of the DW redox couple, indicating that a fast molecularcharge transfer reaction foreruns the interfacial hole injection intoLiFePO₄. This kind of behaviour was not yet reported for molecularwiring or targeting of LiFePO₄. At slower scanning (20 mV/s, themolecular couple is not seen, and the voltammogram is dominated by thewiring current only. Both curves in FIG. 7A were acquired on fresh(non-treated) electrodes with roughly identical film's mass and surfacearea.

The surface coverage of LiFePO₄ with DW was analyzedspectrophotometrically and found to be 0.5 nmol/cm² (referred to the BETsurface area of the electrode material), which is ca. 3 molecules/nm².This surface coverage is similar to that found for TiO₂ (vide ultra) andalso comparable to that reported for the BMABP/LiFePO₄ system: 2.5molecules/nm². Hence, the surface concentration of 2-3 molecules/nm²seems to be representative for monolayer coverage for these relativelysmall organic molecules with one phosphonic anchor. Presumably, thegradual delithiation of LiFePO₄ during repeated cycling from faster toslower scan rates might, actually, caused this effect too. Also shown onFIG. 7A is the behaviour of a blank LiFePO₄ film, which was not treatedby DW. This electrode shows negligible electrochemical activity, as itis expected for a stoichiometric olivine, free from any carbonadditives.

The voltammogram of partly delithiated electrode also shows more clearlythat the wiring current is independent of the scan rate. FIG. 7Bpresents the voltammogram of an electrode, which was delithiated byrepeated cycling, followed by one-hour charging at a constant potentialof 4.2 V. The total passed charge was equivalent to ca. 15% of thetheoretical charge capacity (170 mAh/g) of the used electrode. Thiselectrode still exhibits the wiring effect, albeit the current for the15%-delithiated electrode is ca. 40 times smaller than for the freshelectrode.

To get more insight into the fading of wiring activity, we have testedthe behaviour of a fresh DW/LiFePO₄ electrode during ten subsequent CVscans at various scan rates. FIG. 8 summarizes the data for sixelectrodes; each plot at the given scan rate starts from a virginelectrode, while care was taken that all six electrodes had roughlyidentical film mass and area (≈3 mg/cm²). The molecular couple is stillseen at the scan rate of 100 mV/s (cf. FIGS. 7 and 8). At the scan ratesof 50 and 20 mV/s, we can trace an almost ideal molecular wiringbehaviour, which is also apparent at slower scanning of partly chargedelectrodes. Nevertheless, slower scanning of a virgin electrode confirmsthat the wiring current drops significantly already at the time scale ofcyclic voltammetry.

FIG. 9 shows potential-step chronoamperometry test of a virgin DW-wiredLiFePO₄ electrode. The current is not linear with t^(−1/2), in otherwords the Cotrell-like behaviour is not traceable like for redox wiringof molecules on insulating supports (TiO₂). This is quiteunderstandable, because in our case, the chronoamperometry is notcontrolled by diffusion, but by effects associated with the interfacialmolecular wiring. Consequently, chronoamperometry helps to evaluate thewiring effect itself. During one-hour of constant charging at 4.2 V, wecan pass a charge equivalent to ca. 12% of the total faradic capacity ofthe electrode material (170 mAh/g). This is more explicitly shown inFIG. 9-inset, where the current is expressed in a way conventional inbattery testing. Obviously, charging rates of ca. C/2-C/10 areapplicable for fresh electrodes and shallow charging.

Our data confirm that the wiring current is primarily controlled by thestate of the DW/LiFePO₄ interface, which is most easily described as thelevel of the LiFePO₄ charging. This is further presented on FIG. 10,which compiles the data from cyclic voltammetry (plots like those inFIGS. 4 and 5) and chronoamperometry (FIG. 9). Voltammetric data(points) and chronoamperometry data (line) are reasonably matching. Thewiring current seems to be roughly inversely proportional to the levelof discharge, this is represented by a dashed line in FIG. 9.

The performance of a DW-wired LiFePO₄ olivine is s far from that of theup-to-date carbon-coated LiFePO₄ cathodes for Li-ion batteries. But itis certainly interesting, at least academically, that a monolayer ofmolecules can carry currents, needed for charging of conventionalbatteries. We may reasonably expect further performance upgrade, if theparticle size of the electrode material gets smaller.

FIGURE CAPTIONS

FIG. 1. Vis-NIR spectrum of the working solution of single wall carbonnanotubes dispersed by Ru-complex, Z-907Na/SWCNT (curve A) and pureRu-complex Z-907Na (curve B). The concentration of Ru-complex was 6×10⁻⁴mol/L in both cases, the optical cell thickness was 2 mm.

FIG. 1. Pure LiFePO₄ electrode (with 5% PVDF; total film mass 1.54mg/cm²) treated by dip coating into 6·10⁻⁴ mol/L solution of Z-907Na(left chart) or Z-907Na/SWCNT (right chart). Scan rates (in mV/s): 50,20, 10, 5 for curves from top to bottom. Electrolyte solution is 1 MLiPF₆ in EC/DMC.

FIG. 3. Left chart: Cyclic voltammograms (scan rates 0.1 mV/s);electrolyte solution 1 M LiPF₆ in EC/DMC. Curve A: Electrode fromLiFePO₄ surface-derivatized with Z-907Na/SWCNT (2.04 mg/cm²). Curve B(dashed line): electrode from carbon-coated LiFePO₄ (Nanomyte BE-20,2.28 mg/cm²). Curve C: Electrode from LiFePO₄ surface-derivatized withpyrene butanoic acid/SWCNT (1.83 mg/cm²). The current scale ismultiplied by a factor of 10 for curve B.

Right chart: Galvanostatic charge/discharge cycle; electrolyte solution1 M LiPF₆ in EC/DMC. Curve A: Electrode from LiFePO₄ surface-derivatizedwith Z-907Na/SWCNT (2.04 mg/cm²) charging rate C/5. Curve B (dashedline): electrode from carbon-coated LiFePO₄ (Nanomyte BE-20, 2.28mg/cm²) charging rate C/50.

FIG. 4: Cyclic voltammograms of DW adsorbed on mesoporous TiO₂ film.Scan rates (in mV/s): 200, 100, 50, 20, 10, 5, 2, 1. Inset shows theforward peak current as a function of the square root of the scan rate.

FIG. 5: Cyclic voltammograms of DW adsorbed on mesoporous TiO₂ film.Scan rate 1 mV/s. Ten successive scans were accumulated.

FIG. 6: Cyclic voltammograms of DW adsorbed on LiMnPO₄ electrode. Scanrates (in mV/s): 200, 100, 50, 20, 10, 5, 2, 1. Inset shows the forwardpeak current as a function of the square root of the scan rate.

FIG. 7: Cyclic voltammograms of DW-wired LiFePO₄ electrode. A: Freshelectrode: first scan at 200 mV/s (red), 20 mV/s (blue). For comparison,green line is for LiFePO₄ electrode without DW (20 mV/s). B: Usedelectrode (after 15% charge): scan rates (in mV/s): 20 (red), 10 (blue),5 (green), 2 (black), 1 (magenta).

FIG. 8: Cyclic voltammograms of DW-wired LiFePO₄ electrode. Tensuccessive scans were accumulated for each given scan rate.

FIG. 9: Potential-step chronoamperometry of DW-wired LiFePO₄ electrode.The potential step was from 3.5 V to 4.2 V (3600 s) to 3.5 V (300 s).Inset shows the same data recalculated in C-rate charging vs. chargecapacity of the actual electrode assuming 170 mAh/g as the theoreticalcharge capacity.

FIG. 10: Compilation of the measured wiring currents as a function ofthe level of charging assuming 170 mAh/g (theoretical charge capacity)as the reference 100% charge. Points: data from CV at varying scan ratesbetween 1 to 200 mV/s. Curve: data from potential-step chronoamperometry(3.5-4.2 V (3600 s)-3.5 V). Also shown is a model hyperbola (dashedline) assuming the wiring current were inversely proportional to therelative charge.

REFERENCE LIST

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1. A rechargeable electrochemical cell with improved energy density,comprising cathodic or anodic lithium insertion materials with p- orn-type redox active compounds, said electrochemical cell comprising twocompartments separated by a separating element, the first compartmentcontaining cathodic lithium insertion material and SWCNT attached withp-type redox active compounds and/or the second compartment containinganodic lithium insertion material and SWCNT attached with n-type redoxactive compound said separating element being permeable for lithiumions.
 2. A rechargeable electrochemical cell according to claim 1,comprising: (a) A first electrode compartment comprising cathode lithiuminsertion material with SWCNT attached redox active compound, negativeelectrode and electrolyte. The first oxidation potential of the p-typeredox active polymer compound matches the cathode lithium insertionmaterial. (b) A second electrode compartment comprising anode lithiuminsertion material with SWCNT attached redox active compound, positiveelectrode and electrolyte. The first reduction potential of the n-typeredox active compound matches the anodic lithium insertion material. (c)At least one of the electrode compartments is with redox active moleculeattached SWCNT.
 3. The rechargeable electrochemical cell according toclaim 2, wherein the nano- or sub-micrometer sized cathode lithiuminsertion material is selected from doped or non-doped oxides LiMO₂where M is one or more elements selected from M=Co, Ni, Mn, Fe, W, V,LiV₃O₈ and mix of them; phosphor-olivines as LiMPO₄ where M is one ormore elements selected from with M=Fe, Co, Mn, Ni, VO, Cr and mix ofthem and spinels and mixed spinels as Li_(x)Mn₂O₄ orLi₂CO_(x)Fe_(y)Mn_(z)O₈, etc.
 4. The rechargeable electrochemical cellaccording to claim 2, wherein the nano- or sub-micrometer sized anodiclithium insertion material is selected from carbon, TiO₂, Li₄Ti₅O₁₂,SnO₂, SnO, Si, etc.
 5. The rechargeable electrochemical cell accordingto claim 2, wherein the particle size of the lithium insertion materialsranges from 10 nm to 10 Dm.
 6. According to the claim 2 the redox activemolecule is attached to the SWCNT, either by covalent bonding ornon-covalent bonding or electrostatic interaction.
 7. The rechargeableelectrochemical cell according to claim 6, wherein the redox activecompound is an organic compound selected from equation (II)—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. Theembodiment, D is selected from benzol, naphtaline, indene, substitutedtriarylamine, fluorene, phenantrene, anthracene, triphenylene, pyrene,pentalene, perylene, indene, azulene, heptalene, biphenylene, indacene,phenalene, acenaphtene, fluoranthene, and heterocyclic compoundspyridine, pyrimidine, pyridazine, quinolizidine, quinoline,isoquinoline, quinoxaline, phtalazine, naphthyridine, quinazoline,cinnoline, pteridine, indolizine, indole, isoindole, carbazole,carboline, acridine, phenanthridine, 1,10-phenanthroline, thiophene,thianthrene, oxanthrene, and derivatives thereof, optionally besubstituted. According to a preferred embodiment, D is selected fromstructures of formula (1-11) given below:

in which each of Z¹, Z² and Z³ is the same or different and is selectedfrom the group consisting of O, S, SO, SO₂, NR¹, N⁺(R^(1′))(R^(1″)),C(R²)(R³), Si(R^(2′))(R^(3′)) and P(O)(OR⁴), wherein R¹, R^(1′) andR^(1″) are the same or different and each is selected from the groupconsisting of hydrogen atoms, alkyl groups, haloalkyl groups, alkoxygroups, alkoxyalkyl groups, aryl groups, aryloxy groups, and aralkylgroups, which are substituted with at least one group of formula—N⁺(R⁵)₃ wherein each group R⁵ is the same or different and is selectedfrom the group consisting of hydrogen atoms, alkyl groups and arylgroups, R², R³, R^(2′) and R^(3′) are the same or different and each isselected from the group consisting of hydrogen atoms, alkyl groups,haloalkyl groups, alkoxy groups, halogen atoms, nitro groups, cyanogroups, alkoxyalkyl groups, aryl groups, aryloxy groups and aralkylgroups or R² and R³ together with the carbon atom to which they areattached represent a carbonyl group, and R⁴ is selected from the groupconsisting of hydrogen atoms, alkyl groups, haloalkyl groups,alkoxyalkyl groups, aryl groups, aryloxy groups and aralkyl groups. 8.According to claim 7, preferred embodiments for D may be selected fromstructures (12) and (13) given below:


9. The rechargeable electrochemical cell according to claim 6, whereinthe redox active compound is of the formula (III) as follows:

n=0 to 20 X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ A=F or Cl or Br Ior NO₂ or COOR or Alkyl (C₁ to C₂₀) or CF₃ or COR or OCH₃ or H B=F or Clor Br I or NO₂ or COOR or Alkyl (C₁ to C₂₀) or CF₃ or COR or OCH₃ A=B orA≠B
 10. The rechargeable electrochemical cell according to claim 6,wherein the redox active compound is of the formula (IV) as follows:

n=0 to 20 R=H or C₁ to C₂₀ X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂11. The rechargeable electrochemical cell according to claim 6, whereinthe redox active compound is of the formula (V) to (X) as follows:

n=0 to 20 X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ Y=N or O or S R₁,R₂, R₃, R₄ can be F or Cl or Br I or NO₂ or COOR or Alkyl (C₁ to C₂₀) orCF₃ or COR or OCH₃ or H
 12. The rechargeable electrochemical cellaccording to claim 6, wherein the redox active compound is of theformula (XI) as follows:

Wherein A and B are same or different from H, OR, Cl, Br, F, I, NO2,CF3, COCF3, R is H or (CH₂)_(p)-E_(n)-(CH₂)_(m)—Acc (p=0 to 24, linearor branched or with cycles; n=0 to 24, m=0 to 24, linear or branched orwith cycles; E is —CH═CH—, or —C≡O—, or —OCH₂CH₂—, and Acc is PO₃H₂ orCO₂H or SO₃H or CONHOH or PO₄H₂ or SO₄H₂.
 13. The rechargeableelectrochemical cell according to claim 6, wherein the redox activecompound is of the formula (XII) as follows:

Wherein X and Y are same or different from H, OR, Cl, Br, F, I, NO2,CF3, COCF3, R is H or (CH₂)_(p)-E_(n)-(CH₂)_(m)—Acc (p=0 to 24, linearor branched or with cycles; n=0 to 24, m=0 to 24, linear or branched orwith cycles; E is —CH═CH—, or —C≡O—, or —OCH₂CH₂—, and Acc is PO₃H₂ orCO₂H or SO₃H or CONHOH or PO₄H₂ or SO₄H₂.
 14. The rechargeableelectrochemical cell according to claim 6, wherein the redox activecompound is of the formula (XIII) as follows:

Wherein A, B and C are same or different from H, OR, Cl, Br, F, I, NO2,CF3, COCF3, linear or branched alkyl group from 1 to 20 carbon atoms, Ris H or (CH₂)_(p)-E_(n)-(CH₂)_(m)—Acc (p=0 to 24, linear or branched orwith cycles; n=0 to 24, m=0 to 24, linear or branched or with cycles; Dis —CH═CH—, or —C≡O—, or —OCH₂CH₂—, and Acc is PO₃H₂ or CO₂H or SO₃H orCONHOH or PO₄H₂ or SO₄H₂.
 15. According to claim 12 the most preferredcompound is 12-(2,5-di-tert-butyl-4-methoxyphenoxy) dodecyl phosphonicacid.
 16. The rechargeable electrochemical cell according to claim 6,wherein the redox active compound is a metal complex of the formula(XIV) or (XV) as follows:

wherein M=Fe or Ru or Os n=0 to 20 X=PO₃H₂ or CO₂H or SO₃H or CONHOH orPO₄H₂ or SO₄H₂ P=F or Cl or Br or I or NO₂ or CN or NCSe or NCS or NCO

Wherein B=alkyl (C₁ to C₂₀) or H R, R₁, R₂ is same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or a liniar or branched alkyl(C₁ to C₂₀) or H (where R₃ is an alkyl (C₁ to C₂₀) or H) or comprises anadditional π system located in conjugated relationship with the primaryπ system, the said substituent is of the type—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. wherein theother one(s) of substituent(s) —R, —R₁, —R₂ is (are) the same or adifferent substituent of formula (1), (2) or (3), or is (are) selectedfrom —H, —OH, —R₃, —OR₃, COOH, COCF₃, CN, Br, Cl, F, I, CF3, or —N(R₃)₂,wherein R₃ is a liniar or branched alkyl of 1 to 20 carbon atoms. 17.The rechargeable electrochemical cell according to claim 6, wherein theredox active compound is a metal complex of the formula (XVI) asfollows:

M=Fe or Ru or Os X=F or Cl or Br or I or NO₂ or CN or NCSe or NCS or NCO

Wherein B=liniar or branched alkyl (C₁ to C₂₀) or H R, R₁, R₂ is same ordifferent from COOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ orCF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Br or I or NR₃ or a liniar orbranched alkyl (C₁ to C₂₀) or H (where R₃ is an alkyl (C₁ to C₂₀) or H)or comprises an additional π system located in conjugated relationshipwith the primary π system, the said substituent is of the type—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. wherein theother one(s) of substituent(s) —R, —R₁, —R₂ is (are) the same or adifferent substituent of formula (1), (2) or (3), or is (are) selectedfrom —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F, I, CF3, or —N(R₃)₂,wherein R₃ is a liniar or branched alkyl of 1 to 20 carbon atoms.

Wherein B=alkyl (C₁ to C₂₀) or H R, R₁, R₂ may be same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or alkyl (C₁ to C₂₀) or H whereR₃ is an alkyl (C₁ to C₂₀) or H R, R₁, R₂ is same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or a liniar or branched alkyl(C₁ to C₂₀) or H (where R₃ is a linear or branched alkyl (C₁ to C₂₀) orH) or comprises an additional π system located in conjugatedrelationship with the primary π system, the said substituent is of thetype—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. wherein theother one(s) of substituent(s) —R, —R₁, —R₂ is (are) the same or adifferent substituent of formula (1), (2) or (3), or is (are) selectedfrom —H, —OH, —R₃, —OR₃, COOH, COCF₃, CN, Br, Cl, F, I, CF₃, or —N(R₃)₂,wherein R₃ is a liniar or branched alkyl of 1 to 20 carbon atoms. 18.The rechargeable electrochemical cell according to claim 6, wherein theredox active compound is a metal complex of the formula (XVII) asfollows:

Wherein M=Fe or Ru or Os B=alkyl (C₁ to C₂₀) or H R, R₁, R₂ may be sameor different from COOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃or CF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Br or I or NR₃ or alkyl (C₁to C₂₀) or H where R₃ is an alkyl (C₁ to C₂₀) or H R, R₁, R₂ is same ordifferent from COOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ orCF₃ or COCF₃ or OR₃ or NO₂ or F or Cl or Br or I or NR₃ or a liniar orbranched alkyl (C₁ to C20) or H (where R₃ is a linear or branched alkyl(C₁ to C₂₀) or H) or comprises an additional π system located inconjugated relationship with the primary π system, the said substituentis of the type—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. wherein theother one(s) of substituent(s) —R, —R₁, —R₂ is (are) the same or adifferent substituent of formula (1), (2) or (3), or is (are) selectedfrom —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F, I, CF3, or —N(R₃)₂,wherein R₃ is a liniar or branched alkyl of 1 to 20 carbon atoms. 19.The rechargeable electrochemical cell according to claim 6, wherein theredox active compound is a metal complex of the formula (XVIII) asfollows:

M=Fe or Ru or Os n=0 to 20 X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ orSO₄H₂ P=F or Cl or Br or I or NO₂ or CN or NCSe or NCS or NCO

Wherein B=alkyl (C₁ to C₂₀) or H R, R₁, R₂ may be same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or alkyl (C₁ to C₂₀) or H whereR₃ is an alkyl (C₁ to C₂₀) or H R, R₁, R₂ is same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or a liniar or branched alkyl(C₁ to C₂₀) or H (where R₃ is a linear or branched alkyl (C₁ to C₂₀) orH) or comprises an additional π system located in conjugatedrelationship with the primary π system, the said substituent is of thetype—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. wherein theother one(s) of substituent(s) —R, —R₁, —R₂ is (are) the same or adifferent substituent of formula (1), (2) or (3), or is (are) selectedfrom —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F, I, CF3, or —N(R₃)₂,wherein R₃ is a liniar or branched alkyl of 1 to 20 carbon atoms. 20.The rechargeable electrochemical cell according to claim 6, wherein theredox active compound is a metal complex of the formula (XIX) asfollows:

M=Fe or Ru or Os n=0 to 20 X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ orSO₄H₂ P=CN or NCSe or NCS or NCO

Wherein B=alkyl (C₁ to C₂₀) or H R, R₁, R₂ may be same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or alkyl (C₁ to C₂₀) or H whereR₃ is an alkyl (C₁ to C₂₀) or H R, R₁, R₂ is same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or a liniar or branched alkyl(C₁ to C₂₀) or H (where R₃ is a linear or branched alkyl (C₁ to C₂₀) orH) or comprises an additional π system located in conjugatedrelationship with the primary π system, the said substituent is of thetype—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. wherein theother one(s) of substituent(s) —R, —R₁, —R₂ is (are) the same or adifferent substituent of formula (1), (2) or (3), or is (are) selectedfrom —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F, I, CF3, or —N(R₃)₂,wherein R₃ is a liniar or branched alkyl of 1 to 20 carbon atoms. 21.The rechargeable electrochemical cell according to claim 6, wherein theredox active compound is a metal complex of the formula (XX) as follows:

M=Fe or Ru or Os n=0 to 20 X=PO₃H₂ or CO₂H or SO₃H or CONHOH or PO₄H₂ orSO₄H₂ P=CN or NCSe or NCS or NCO or pyrazine.

Wherein B=alkyl (C₁ to C₂₀) or H R, R₁, R₂ may be same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or alkyl (C₁ to C₂₀) or H whereR₃ is an alkyl (C₁ to C₂₀) or H R, R₁, R₂ is same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or a liniar or branched alkyl(C₁ to C₂₀) or H (where R₃ is a linear or branched alkyl (C₁ to C₂₀) orH) or comprises an additional π system located in conjugatedrelationship with the primary π system, the said substituent is of thetype—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. wherein theother one(s) of substituent(s) —R, —R₁, —R₂ is (are) the same or adifferent substituent of formula (1), (2) or (3), or is (are) selectedfrom —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F, I, CF3, or —N(R₃)₂,wherein R₃ is a liniar or branched alkyl of 1 to 20 carbon atoms.

Wherein B=alkyl (C₁ to C₂₀) or H R, R₁, R₂ may be same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or alkyl (C₁ to C₂₀) or H whereR₃ is an alkyl (C₁ to C₂₀) or H R, R₁, R₂ is same or different fromCOOR₃ or PO₃R₃ or SO₃R₃ or CONR₃OR₃ or SO₄R₃ or COR₃ or CF₃ or COCF₃ orOR₃ or NO₂ or F or Cl or Br or I or NR₃ or a liniar or branched alkyl(C₁ to C₂₀) or H (where R₃ is a linear or branched alkyl (C₁ to C₂₀) orH) or comprises an additional π system located in conjugatedrelationship with the primary π system, the said substituent is of thetype—R=πRal) or -(Ral) wherein π represents schematically the π systemof the aforesaid substituent, Ral represents an aliphatic substituentwith a saturated chain portion bound to the π system, and wherein qrepresents an integer, indicating that π may bear more than onesubstituent Ral. wherein at least one of substituents —R, —R₁, —R₂ is offormula (1), (2) or (3)

wherein p is an integer from 0 to 20, wherein Rar is a H or monocyclicor oligocyclic aryl from C6 to C22, wherein -Ral is —R1 or —O—R1 or—N(R1)₂ or —NHR1 or

wherein R1, R′1 are same or different from —CH₂PO₃H₂, —CH₂CO₂H,—CH₂SO₃H, —CH₂CONHOH, —CH₂PO₄H₂, —CH₂SO₄H₂, x≧0, and 0<n<20. wherein theother one(s) of substituent(s) —R, —R₁, —R₂ is (are) the same or adifferent substituent of formula (1), (2) or (3), or is (are) selectedfrom —H, —OH, —R₃, —OR₃, COOH, COCF3, CN, Br, Cl, F, I, CF3, or —N(R₃)₂,wherein R₃ is a liniar or branched alkyl of 1 to 20 carbon atoms.